AutoLISP applications are stored in editable ASCII text files with the .lsp extension. These files generally have a header portion that describes a routine,
its use, and any specific instructions. This header might also include comments that
document the author and the legal information regarding the use of the routine. Comments
are preceded by a semicolon (;). You can view and edit these files with a text editor
or word processor that can produce an ASCII text file.

Before you can use an AutoLISP application, it must first be loaded. You can use the
APPLOAD command or the AutoLISP load function to load an application. Loading an AutoLISP application loads the AutoLISP
code from the LSP file into your system’s memory. You must specify a relative support
path in the Filename parameter if the LSP file is not located in the Support File
Search Path.

Loading an application with the load function involves entering AutoLISP code at the command prompt. If the load function is successful, it displays the value of the last expression in the file
at the command prompt. This is usually the name of the last function defined in the
file or instructions on using the newly loaded function. If load fails, it returns an AutoLISP error message. A load failure can be caused by incorrect coding in the file or by providing the wrong file
name. The syntax for the load function is

(load filename [onfailure])

This syntax shows that the load function has two arguments: filename, which is required, and onfailure, which is optional. When loading an AutoLISP file at the Command prompt, you typically
supply only the filename argument. The following example loads the AutoLISP file newfile.lsp.

Command: (load “newfile”)

The .lsp extension is not required. This format works for any LSP file in the current library
path.

To load an AutoLISP file that is not in the library path, you must provide the full
path and file name as the filename argument.

Windows

Command: (load “d:/files/morelisp/newfile”)

Mac OS

Command: (load “/files/morelisp/newfile”)